This sample demonstrates the LinkShiftingTool, which is an extra tool that can be installed in the ToolManager to allow users to shift the end point of the link to be anywhere along the sides of the port with which it remains connected. This extension tool is defined in its own file, as LinkShiftingTool.js.
This only looks good for ports that occupy the whole of a rectangular node. If you want to restrict the user's permitted
sides, you can adapt the LinkShiftingTool.doReshape
method to do what you want.